Sewing machine feeder drive means



R. J. BOSER SEWING MACHINE FEEDER DRIVE MEANS Oct. 31, 1967 2 She ets-Sheet 1 Filed Jan. 4, 1965 AII'III INVENTOR RONALD J BOSER 7 ATTORNEY.

Oct. 31, 1967 R. J. sosam SEWING MACHINE FEEDER DRI VB MEANS 2 Sheets- Shem Filed Jan. 4, 1965 United States Patent 3,349,734 SEWING MACHINE FEEDER DRIVE MEANS Ronald J. Eoser, Huntington, N.Y., assignor to B&W Mfg. Co., Inc., New York, N.Y., a corporation of New York Filed Jan. 4, 1965, Ser. No. 423,024 1 Claim. (Cl. 112203) ABSTRACT OF THE DISCLOSURE This invention relates to an improved feeder drive for a plurality of sewing machines for positively feeding a work piece to a plurality of synchronized sewing machines. The feeder drive mechanism comprises a feeder drive mechanism which includes a power input shaft, a power output shaft, a worm gear connected to and driven by the input shaft, an output gear connected to and driving said input shaft, a worm gear having a spiral tooth formed thereon whereby the groove formed between adjacent portions of the spiral tooth is of constant width, the groove having portions of increasing pitch, a portion of decreasing pitch and a portion having no pitch, the output gear having a plurality of toothed means formed thereon, at least one of the output geared tooth means being positively engaged and driven by the spiral tooth of the worm gear at a time.

The present invention relates in general to the sewing machine art and more specifically to an improved feeder drive means for positively feeding a work piece to a plurality of synchronized sewing machines operating on a single work piece.

Attempts have previously been made at arranging a plurality of sewing machines to perform several successive or simultaneous sewing operations on a single work piece under the control of a single operator. However these attempts have been less than completely successful due to the fact that positive synchronization of the different machines was difficult to achieve. One of the most difficult problems encountered in the attempt to synchronize the machines was in the feeder mechanism. This was necessary to assure that the work piece was positively advanced past each machine station simultaneously and at an exact rate and was then stopped for the duration of the stitching operation of the needle and then advanced again. Any slight variation in the speed of the feed mechanisms of the various sewing machines caused injury to the work piece or tended to bend or break the needles of the machines, or else resulted in folds in the work piece between the machines that had to be constantly supervised by an operator. Any and all of these problems not only slowed the sewing operation but also greatly increased its cost.

The foregoing problems have been overcome, to a large extent, by replacing the individual feed mechanisms of the sewing machines by an endless belt conveyor drive which is common to all of the machines operating on a single work piece. Such a conveyor was operated by a unidirectional clutch which was synchronized to advance and then to stop the conveyor and the work piece during the stitching operation of the sewing needles. This drive method has proven generally successful in overcoming the problems previously encountered in simultaneously operating a plurality of sewing machines. However it has been found that the speed of operation has been significantly limited with this feeder device, the maximum speed attainable being approximately 1500 stitches per minute as compared to speeds of 3000 stitches per minute attainable with sewing machines operated singly.

It has been found that conveyor feed mechanisms driven by unidirectional clutches are limited in the speed at which they may be driven due to the fact that, at speeds higher than 1500 stitches per minute, the inertia of the endless conveyor and the work piece tend to override the clutch so that the work piece is not stationary during the stitching operation of the sewing needles. As a result, operation at high speeds often broke or bent the needles causing costly shut downs for repair as well as possibly damaging the work piece.

Furthermore, it has been found that the unidirectional clutch drive tends to be noisy in operation and does not evenly or uniformly accelerate and decelerate the conveyor and the work piece so that damaging stresses are often applied thereto.

The present invention provides a feeder drive mechanism which uniformly accelerates and] then decelerates the conveyor and the work piece and then positively holds them stationary during the stitching operation of the sewing needles. As a result, synchronized sewing machines utilizing the present feeder drive means may be operated at speeds much higher than those now possible.

Accordingly, the present invention comprises a feeder drive mechanism including a power input shaft, a power output shaft, a worm gear connected to and driven by said input shaft, an output gear connected to and driving said output shaft, the worm gear having a spiral tooth formed thereon whereby the groove formed between adjacent portions of the tooth is of substantially constant width, the groove having'a portion of increasing pitch, a portion of decreasing pitch, and a portion having no pitch, the output gear having a plurality of tooth means formed thereon, at least one of the output gear tooth means being positively engaged and driven by the spiral tooth of the Worm gear at a time.

The various features which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a plan view of a pair of sewing machines having the feeder drive mechanism of the present invention;

FIG. 2 is a plan view of a detail of the drive mechanism of the present invention; and

FIG. 3 is a view of the drive mechanism taken along line 3-3 of FIG. 2, with th worm gear shown in phantorn.

Referring to FIG. 1, the present invention is illustrated comprising two sewing machines 10 and 12 connected to and supported by a suitable frame (not shown). The sewing machines are shown arranged on opposite sides of a feeder conveyor which is made up of any number of endless belts 14. While only two sewing machines are illustrated it will be understood that any desired number of sewing machines may be mounted on the frame. It will also be understood that the machines may be arranged in tandem as well as oppositely, as shown.

Each of the sewing machines 10 and 12 may be of any well known construction, e.g. a Singer-type sewing machine or the like. Each of the sewing machines is of conventional construction, except as herein modified. Generally, each machine includes a main drive shaft, 16 and 18, with drive pulleys 20 and 22 connected thereto. The drive shaft operates the needles of the machines in a conventional manner. The drive pulley 20 of sewing machine 10 is driven by a drive belt 24 from a pulley 26 driven by a power input shaft 28 which extends through the feeder drive mechanism, generally indicated at 30, which is powered by a motor 32 connected thereto by any conventional means such as belt 34. The belt 24 driving sewing machine passes over idler pulleys 36 and 38 which are arranged to maintain the tension thereon in a manner well known in the art. The drive pulley 22 of sewing machine 12 is driven by a drive belt 40- which is driven by a pulley 42 connected to a shaft 44 which extends to the opposite side of the feeder conveyor belts 14 where it is connected via pulley 46 and belt 48 to a second pulley 50 driven by the power input shaft 28. To prevent slippage and assure positive synchronization of the two sewing machines 10 and 12, belts 24, 40 and 46, are formed with a series of transversely extending lands and grooves thereon which mesh with complementary lands and grooves formed on the pulleys to which they are connected.

The endless belts 14 of the feeder conveyor are supported by idler rollers 52, 54 and 56 at both ends of the belts and by a drive roller 58 arranged at one end of the belts. The drive roller 58 is connected via shaft 60 and a pair of angle gears 62 to a power output shaft 64 of the feeder drive mechanism 30'.

The feeder drive mechanism, as previously noted, has a power input shaft 28 extending therethrough journaled on bearings (not shown). The power output shaft 64 is arranged at right angles to the power input shaft and is also journaled on suitable bearings (not shown). A worm gear 66 is connected to and is driven by the power input shaft. The worm gear has a spiral tooth 68 formed thereon which has a portion of increasing pitch, a portion of decreasing pitch, and a portion having no pitch. The tooth 68 may have a varying width so that the groove formed between adjacent portions thereof has a substantially constant width. An output gear 70, comprising a disc member 72 having a plurality of tooth means 74 extending outwardly from one face thereof, is connected coaxially to the end of the power output shaft 64. The tooth means 74 may be substantially cylindrical in shape or frusto-conical, as shown, and are arranged to extend outwardly from the face of the disc member 72 opposite from the face which is connected to the output shaft 64. The tooth means are arranged around the face of the disc member substantially equidistant from the. axis of the output shaft with the axes of the tooth means substantially parallel to the axis of the output shaft. The tooth means are connected to the disc member 72 by shanks 76 of reduced diameter which fit into mating holes in the disc member. The shanks are held in the holes by any suitable means such as set-screws 78. Preferably the tooth means 74 are arranged to rotate on the shanks 76 and may, if desired, be provided with suitable bearings.

The output gear 70, and the output shaft 64, are arranged relative to the power input shaft 28 and the worm gear 66, so that at least one tooth means 74 of the output gear at a time are engaged between and driven by adjacent portions of the tooth 68 of the worm gear. Furthermore, the maximum diameter of the tooth means 74 is substantially equal to the maximum width of the groove formed on the worm gear so that there is little or no play therebetween. Also, the groove is arranged to have a cross section which is complementary to the shape of the tooth means 74. Thus when the tooth means 74 of the output gear 70 are frusto-conical in shape, the spiral tooth 68 of the worm gear has a tapering cross section forming a groove which closely conforms to the shape of the tooth means 74. This arrangement has the advantage that the spiral tooth 68 of the worm gear has substantially greater strength than would be the case if it were formed with a square cross section. This feature is especially important in the portions of the spiral tooth where the pitch is varied and the thickness of the spiral tooth changes.

The relative spacing of adjacent tooth means 74 on the output gear 70 and the length of the worm gear 66 is such that as one tooth means 74 is being disengaged from the worm gear the next adjacent tooth means is being engaged by the worm gear so that there is constant engagement of the output gear by the worm gear. Due to the fact that the pitch of the spiral tooth 68 of the worm gear aries it would not be possible to have more than one tooth means 74 engaged thereby at a time. Furthermore, to insure the smooth transmission of power from the worm gear to the output gear the pitch of the spiral tooth 68 at both ends should be substantially equal, otherwise a sudden change in velocity would be imparted to the output gear as successive tooth means 74 were engaged by the worm gear.

In operation, with a worm gear having a spiral tooth formed with a portion having an increasing pitch, followed by a portion having a decreasing pitch, followed by a portion having no pitch, as a first tooth means 74 of the output gear is engaged by the spiral tooth 68 of the output gear, the output gear is first accelerated by the portion of the spiral tooth having an increasing pitch, and then decelerated by the portion of the spiral tooth having a decreasing pitch, and is then held stationary by the portion of the spiral tooth having no pitch. The first tooth means is then disengaged from the worm gear and the operation is repeated with the next succeeding tooth means on the output gear. The accelerating, decelerating and stationary motion of the output gear is transmitted to the feeder conveyor 14 and the work piece being transported thereby. Furthermore, the operation of the sewing machines 10 and 12, being driven from the power input shaft 28 which also drives the worm gear 66, is positively synchronized with the movement of the conveyor feeder 14' such that the stitching operation of the needles of the sewing machines occurs during the period that the conveyor feeder is maintained stationary.

As a result of the conveyor feeder drive mechanism of the present invention the conveyor feeder is always positively engaged with the drive mechanism powering the sewing machines, i.e. .a tooth means 74 on the output gear is always limited in its motion in both the forward and the reverse direction by the engaging portions of the spiral tooth on the worm gear. Since there is no possibility with the present invention that the inertia of the conveyor feeder and the work piece will cause them to move during the stitching operation of the sewing machines, as was possible at high speeds with the clutch operated feeder drive mechanisms of the prior art, the incidence of bent or broken sewing needles and damage to the work piece is greatly reduced while, at the same time, production is greatly increased, all with a reduction in the attention required of an operator, greatly increasing the efiiciency and economy of the operation. Furthermore, since the conveyor feeder and the work piece are smoothly and uniformly accelerated by the feeder drive mechanism of the present invention, the stresses applied, and consequently damage to the work piece is greatly reduced. This feature also reduces the vibration of the machine far below that resulting from the clutch operated feeder mechanisms of the prior art, increasing the operating life thereof. This reduction in the vibration of the machine also has the desirable result of reducing the noise produced during the operation of the machine.

While the worm gear has been described as having a spiral tooth with a portion of increasing pitch followed by a portion having a decreasing pitch, followed by a portion having no pitch, these portions need only be relative with respect to the output gear. Thus an actual spiral tooth may first have a portion of decreasing pitch, followed by a portion having no pitch, followed by a portion of increasing pitch, with ends of the spiral tooth having the same pitch so that there are no abrupt changes in the speed of the output gear as one of its tooth means is disengaged from the worm gear and the next tooth means is engaged.

It will also be appreciated that the spacing of the stitches may be varied with the present arrangement relatively simply by changing the gear ratio of the bevel gears 62 connecting the output shaft 64 to the feeder conveyor drive roller shaft 60. The spacing of the stitches may also be varied, although not as simply, by changing the ratio between the worm gear 66 and the output gear 70.

A further feature of the present arrangement resides in the fact that the connection between the sewing machine 12 and the feeder drive mechanism 30, and the feeder conveyor drive roller 58 and feeder drive mechanism 30, is through shafts 44 and 60. These shafts, as well as the shafts carrying the conveyor belt idler rollers 52, 54 and 56, may be elongated to the left in FIG. 1 so that, with additional, or wider, belts 14 wider work pieces may be handled by the apparatus. Furthermore, since the various connections may be easily arranged to be adjustably positioned along these shafts in a manner Well known in the art, the width of the work piece being operated on by the two sewing machines may be varied at will.

A modified embodiment of the present invention may be used where the driving force transmitted from the worm gear to the output gear is so great as to render the mounting of the output gear on the end of the output shaft impractical. In this alternative arrangement the tooth means of the output gear are arranged perpendicular to the gear axis around the outer periphery of the gear. -In such an arrangement the plane of the output gear would intersect the axis of the worm gear. The worm gear would be modified so as to have a concave outer surface conforming to the curvature of the output gear. The relationship between the spiral tooth of the worm gear and the teeth of the output gear would remain substantially like that disclosed with respect to the preferred embodiment of the invention. In this arrangement, however, the output shaft could be supported by bearings on both sides of the output gear, increasing the forces which could be transmitted thereby.

While in accordance with the provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claim, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

Apparatus for simultaneously performing ,a plurality of sewing operations on a given work piece comprising a frame, a plurality of sewing machines fixedly secured to said frame, each of said sewing machines having a sewing needle, ,a conveyor means common to and cooperatively associated with each of said machines for carrying a work piece past each of said sewing machines, said 4 conveying means including a drive roller and a plurality of spaced idler rollers, an endless conveyor belt threaded over said idler rollers and said drive roller, a drive mechanism for synchronizing the sewing operation with the drive of said conveyor belt, said drive mechanism includ- 5 ing a power input shaft connected at one end to a source of power and at the other end to means for driving the needles of said respective sewing machines, a power output shaft, means connecting said output shaft in driving relationship to said drive roller of said conveyor means, 10 a worm gear connected to .and driven by said input shaft, an output gear connected to and driving said output shaft, said worm gear having a spiral tooth formed thereon whereby the groove formed between adjacent portions of said tooth is of substantially constant width, said groove having a portion of increasing pitch, a portion of decreasing pitch, and a portion having no pitch, said output gear comprising a disc member connected to the other end of said output shaft, said disc member having a plurality of tooth means extending outwardly from one face thereof, said tooth means being substantially frusto-conically shaped with the axes thereof arranged substantially parallel to and disposed around the face of said disc member substantially equidistant from the axis of said output shaft, said tooth means being arranged to rotate about their individual axes, said spiral tooth of said worm gear having a tapered cross section forming a groove which is complementary to said frusto-conical tooth means, said worm gear engaging said output gear and arranged to positively advance said conveyor means and for positively maintaining said conveyor means stationary in synchronization with the sewing operations of said sewing machines.

References Cited UNITED STATES PATENTS 5 JORDAN FRANKLIN, Primary Examiner. RI HA ANLAN, J ml t 

